Different types of single crystalline gallium nitride thin films grown directly on vicinal (001) gallium arsenide substrates

摘要

The approach of direct growth of GaN on vicinal (001) GaAs substrates, by RF-plasma source molecular beam epitaxy, has been investigated. It has been found possible to grow GaN thin films with several different kinds of crystal structure: polycrystalline hexagonal, single-crystalline hexagonal with (0001) or (-1012) orientation and single-crystalline cubic with epitaxial relationship to the GaAs substrate. The GaN crystal structure was controlled by the Gaas surface nitridation, the annealing of an initial low temperature GaN buffer layer and the N/Ga flux ratio conditions. It was also found that cubic or inclined C-axis hexagonal (1012) crystals could overgrow on initial polycrystalline or mixed phase GaN buffer layers.